Question

我将这种风格融入ResourceDictionary。这是一个ToggleButton的列表。我为每个按钮添加了一个contextMenu，我想将click事件交给viewmodel。我有方法Editindicator进入viewmodel。当我运行项目并单击上下文菜单项时，它会断开并显示此错误“{”找不到方法的目标点击。“}”。我认为这个错误是由于menuitem丢失了viewmodel的datacontext。有人可以帮忙吗？非常感谢您的建议。

<Style x:Key="ListBoxStyleIndicador" TargetType="{x:Type ListBoxItem}">
        <Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
    <Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
    <Setter Property="Padding" Value="2,0,2,0"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate x:Name="ListBoxStyleIndicadorTemplate" TargetType="{x:Type ListBoxItem}">
                <Border x:Name="Bd"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        Background="{TemplateBinding Background}" 
                        Padding="{TemplateBinding Padding}" 
                        SnapsToDevicePixels="true">
                    <Controles:ToggleButtonIndicador 
                        Content="{Binding NombreIndicador}" 
                        IdBIIndicadores="{Binding IdBiIndicadores}" 
                        IsChecked="{Binding IsSelected, Mode=TwoWay, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBoxItem}}}" 
                        Style="{DynamicResource BotonNegro}"
                        Padding="6,2"                             
                        ToolTip="{Binding Descripcion}">
                        <Controles:ToggleButtonIndicador.ContextMenu >
                            <ContextMenu>
                                <MenuItem Header="Editar">
                                    <MenuItem.Icon>
                                        <Image Source="{DynamicResource ImagenBotonEditar}" />                                            
                                    </MenuItem.Icon>
                                    <Interactivity:Interaction.Triggers>
                                        <Interactivity:EventTrigger EventName="Click">
                                            <cal:ActionMessage MethodName="EditIndicator" />
                                        </Interactivity:EventTrigger>
                                    </Interactivity:Interaction.Triggers>
                                </MenuItem>                                  
                            </ContextMenu>
                        </Controles:ToggleButtonIndicador.ContextMenu>
                    </Controles:ToggleButtonIndicador>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Setter Property="IsSelected" Value="{Binding Seleccionado, Mode=TwoWay}"/>        
</Style>

Answer 1

由于ContextMenu不是Visual树的一部分，因此您不会引用为您的UserControl设置的ViewModel的DataContext。有两种方法可以为控件获取datacontext -

Set explicitly dataContext for your ContextMenu using the PlacementTarget。请看我的答案 - cannot set tooltip in style
Use Proxy binding.请在此处查看我的回答 - Binding from items in ItemsControl to ItemControl's DataContext

编辑：对于DataContext，您可以这样做 -

<Controles:ToggleButtonIndicador Tag="{Binding DataContext, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}>
                        <Controles:ToggleButtonIndicador.ContextMenu >
                            <ContextMenu DataContext={Binding PlacementTarget.Tag, RelativeSource={RelativeSource Self}}>
                                <MenuItem Header="Editar">
                                    <MenuItem.Icon>
                                        <Image Source="{DynamicResource ImagenBotonEditar}" />                                            
                                    </MenuItem.Icon>
                                    <Interactivity:Interaction.Triggers>
                                        <Interactivity:EventTrigger EventName="Click">
                                            <cal:ActionMessage MethodName="EditIndicator" />
                                        </Interactivity:EventTrigger>
                                    </Interactivity:Interaction.Triggers>
                                </MenuItem>                                  
                            </ContextMenu>
                        </Controles:ToggleButtonIndicador.ContextMenu>
                    </Controles:ToggleButtonIndicador>

我抱怨你的viemodel绑定到UserControl的DataContext属性。

Answer 2

如果它可以帮助任何人。在使用以下示例代码之前，强烈建议您阅读CodeProject上的Attaching a Virtual Branch to the Logical Tree in WPF。你会知道问题出现的原因以及如何优雅地解决问题。

以下是快速示例。

// Add a DataContextBridge.
<UserControl.Resources>
    <FrameworkElement x:Key="DataContextBridge" />
</UserControl.Resources>

// Bind.
<UserControl.DataContext>
    <Binding
        Mode="OneWayToSource"
        Path="DataContext"
        Source="{StaticResource DataContextBridge}" />
</UserControl.DataContext>

// Trigger a click event.
<ContextMenu>
    <MenuItem>
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Click">
                <ei:CallMethodAction
                    TargetObject="{Binding Source={StaticResource DataContextBridge}, Path=DataContext}"
                    MethodName="OnClick" />
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </MenuItem>
</ContextMenu>

感谢。

不用手MenuItem点击进入viewmodel

2 个答案: